In the manufacturing of semiconductor devices, a silicon wafer is first produced. These wafers are created by growing a single silicon crystal. This crystal is then processed through such steps as the evaluation and testing of the physical properties of the crystal, grinding the crystal to a desired diameter, sawing the single silicon crystal into wafers, marking the wafers with a laser, grinding the wafers to a specified thickness, edge rounding, etching away damaged areas, and polishing the surface.
These wafers are then processed into individual dies by the deposition and placement of structures and layers onto the wafers. Once each of the dies has been tested for functionality, the dies are separated from the wafer using a saw. Generally, sufficient space is left between adjacent dies to allow for the width of a saw blade during cutting. This space between the dies is referred to as a scribe line. These scribe lines usually contain test structures used to verify the properties of the die.
Unfortunately, the physical process of sawing the wafer may damage the physical structure of the dies. For example, the saw could crack the silicon crystal of the wafer, and these cracks could then propagate through the dies. The saw may also cause a partial or complete delamination of the dies, essentially pulling off some of the layers that have been deposited onto the wafer. Additionally, the test structures, which could be located in the scribe line itself, can also cause cracking when the die is cut. Damage such as this would render the dies unusable and ruin the commercial value of the dies.
One attempt to contain this cracking and delaminating consists of depositing a seal ring onto the wafers in order to stop the propagation of the die saw cracks. However, this seal ring occasionally fails, in which case there is nothing further to prevent the cracks or delamination from propagating and ruining the commercial use of the die.
Another attempt to contain cracks and delamination is to use dummy metal structures 103 in the scribe line 102, as described in FIG. 1. These dummy metal structures 103 are normally used to balance the metal density during chemical mechanical polishing (CMP). However, when they are used appropriately, they can act as a precipitate in order to stop dislocation movement, and prevent cracks and delamination from spreading. These dummy metal structures 103 could be placed all around the die, or else they could be placed in areas where potential cracking would be concentrated, such as the corners of the die. While these dummy metal structures 103 are typically square in shape, an “L” shape has also been used to prevent cracks from propagating. However, neither of these shapes is necessarily the best shape to use in stopping these cracks and delamination, from either a technical or a meaningful sense. Therefore, a system and method is needed to prevent or reduce the cracks and delamination from propagating beyond the scribe line.